PHP function to replace internal links in articles PHP keyword replacement (including the function of shielding and restoring original links)

/*
* PHP替换文章内链
* by bbs.it-home.org
*/
function _base64_encode($t,$str) {
 return $t.""".base64_encode($str).""";
}
function _base64_decode($t,$str) {
 return $t.""".base64_decode($str).""";
}
function _keylinks($txt, $replacenum = '',$link_mode = 1) {
 /* 屏蔽原始的 a */
 $replace_a = "_base64_encode('ori_a=','\0')";
 $replace1_a = "stripslashes(base64_decode('\1'))";
 $search_a = "/.*?/isxe";
 $search1_a = "/ori_a=(".*?")/isxe";
 $txt = preg_replace($search_a, $replace_a, $txt);
 /* 屏蔽alt title src */
 $search = "/(alts*=s*|titles*=s*|srcs*=s*)   # find       (["'])?(.*?)    # find single or double quote
      (?(2)\2|s+?)  # if quote found, match up to next matching
             # quote, otherwise match up to next space
      /isxe";
 $replace = "_base64_encode('\1','\3')";
 $replace1 = "_base64_decode('\1','\3')";
 $txt = preg_replace($search, $replace, $txt);

 echo $txt;
 echo "http://bbs.it-home.org/";
    $replacement[] = ''.$v.'';
   } else {
    $word1[] = '/'.preg_quote($v[0], '/').'/';
    $word2[] = $v[0];

    $replacement[] = ''.$v[0].'';
   }
  }
  if($replacenum != '') {
   $txt = preg_replace($word1, $replacement, $txt, $replacenum);
  } else {
   $txt = str_replace($word2, $replacement, $txt);
  }
 }
 */

 /* 还原原始 a */
 $txt = preg_replace($search1_a, $replace1_a, $txt);
 /* 还原alt title src */
 $txt = preg_replace($search, $replace1, $txt);

 echo $txt;

 return $txt;
}

$con = "　　性生活过度伤害前列腺。和谐美满的性生活，是男女生理的天然需要，是夫妻感情的粘合剂之一，是夫妻生活必不少的重要组成部分。但是有此想法的夫妻可要注意了。因为做x爱时间并非越长越好，夫妻的性生活的和谐与美满也不由性xai时间的长短来决定。反而，超时性XZ爱，还会影响到夫妻的健康，甚至引发各种疾病。
";
_keylinks($con);
?>